Interfacing circuitry and method for multiple-discharge gaseous display and/or memory panels

ABSTRACT

An interface circuit and method for multiple-discharge gaseous display and/or memory panels utilizing the time characteristics of individual discharge units in a multiple-discharge panel to control the status of individual units without affecting the status of individual discharge units. A low-level voltage signal from an addressing logic system is translated into a high-voltage unidirectional pulse which is added to a periodic alternating voltage at selected times to rapidly modify the charge storage at a selected discharge unit to control on and off states of selected discharge units.

States t [72] Inventors William 1E. Johnson;

Larry J. Schmersal, hoth oi Toledo, Ohio [21] Appl, No. 699,170

[22] Filed Jan. 19, 1968 [45] Patented Nov. 2, 1971 [73] Assignee Owens-Illinois, inc.

[54] HNTERFACING CllRCUlTlllY AND METHOD FOR MULTIPLE-DISCHARGE GASEOUS DISHLAY AND/01R MEMORY PANELS 10 Claims, 8 Drawing Figs.

[52] U.S. C1 t. 340/324,

[51] 11nt.C1 ..G06k15/18 [50] Field of Search 315/169,

[ 56] References Cited UNITED STATES PATENTS 3,364,388 1/1968 Zin 315/166 3,499,167 3/1970 Baker et a1. 315/169 2,123,457 7/1938 Andersen 340/336 2,892,968 6/1959 Kallmann et al. 315/169 3,364,386 l/1968 Segawa et a1. 315/169 3,432,724 3/1969 Frost 315/169 3,559,190 1/1971 Bitzer etal 340/173 Primary Examiner-John W. Caldwell Assistant Examiner-Marshall M. Curtis Attorneys-Charles S, Lynch and W. A. Schaich PATENTEMnvz I97] 346184071 SHEET 3 [IF 4 The present invention interface circuit and method for supplying operating potentials to multiple gas discharge display/memory panels and, in particular, relates to a circuit and method for adding a high-voltage unidirectional pulse to source of sustaining potential at selected time intervals to control operation of selected individual discharge units in a multipie-unit discharge gas display and/or memory panel.

The objects of the invention include the provision of a simplitied low-cost interface circuit between a low-voltage addressing logic circuitry and a high-voltage gaseous discharge display and/or memory device; the provision of a method of reducing the time required to effect turn-on and turnoff ofindividual discharge units in a panel or such discharge units; the prevention of interaction between on-oh signals and sustaining signals to the discharge panel, and a method of utilizing the time characteristics of individual discharge units of a matrix display panel of the electric charge storage type.

The invention will be described in connection with a gas discharge display panel or" the type disclosed in the application of Baker et al., tiled Nov. 24-, 1967, her. No. 686,3ii4 and entitled Gas Discharge Display-Memory Device and Method, now US. Pat. hlo. 3,499,167.

Multiple gas discharge display and/or memory panels of the type with which the present invention is concerned are characterized by a gaseous medium, usually a mixture of two gases at a relatively high gas pressure, in a thin gas chamber or space between a pair of opposed dielectric charge storage members which are backed by conductor members, the conductor members backing each dielectric member being transversely oriented to define a plurality of discrete discharge volumes and constituting a discharge unit. in some cases, the discharge units may be additionally defined by physical structure such as perforated glass plates and the like. However, in the above-identitied patent, physical barriers and isolation members have been eliminated. in both cases, charges (electrons and ions) produced upon ionization of the gas of a selected discharge unit, when proper alternating operating potentials are applied to selected conductors thereof, are collected upon the surfaces of the dielectric at specifically defined locations and constitute an electrical field opposing the electrical held which created them. Both the rate of collection of these charges and the total amount of charge produced in a single discharge depends on the voltage details of the applied voltage magnitude and time relationship that the method of the present invention is based.

The above and other advantages and features of the invention will be better understood when considered with the following specification and accompanying drawings wherein:

FIGS. Mr and t8 are diagrammatic illustrations of a gas discharge pane] and associated circuit for carrying out the invention,

Fit). 2 is an electrical schematic ofa preferred form ofpulse generating circuit incorporated in the invention,

FMS. .il' waveform diagrams which are used for pur poses ofexplaining the operation of the invention.

With reference now to the drawings, l ltifi. tilt and lb illusirate a gas discharge display/memory panel disclosed in the above-identified .ter et al. patent, in which glass support members ill and have formed on their opposing surfaces conductor arrays ll?) and respectively. Dielectric members or coatings id and is have surfaces l7 and ill, respectively, which form charge storage surfaces for storage of charges (electrons and ions) generated upon discharge (ionization) of individual discharge units, respectively.

The surfaces l? and of dielectric members M and 16, respectively, are spaced apart by spacer to form a thin gas chamber or space 2t) and spacer it" or an additional sealant 1158 may be utilized to form a complete hermetic seal for the gas chamber An ionizable gas medium is placed in gas chamber or space at a pressure of about one-half atmosphere or greater. Support members it) and ill are of sufficient size and strength to withstand forces due to any pressure differentials between pressure of the gas within space 2t) and ambient pressure and with a minimum deflection. in the dis closed tube there are no physical obstructions or structures in the gas chamber and due to the pressure, a plurality of discrete discharges can occur within chamber 21h without detrimental interaction to the display or memory functions of individual discharge units, even though the conductors of the conductor arrays are spaced no more than at 30 mils center-to-center spacing. it is to be understood that the invention may be applied with equal facility and results to display/memory panels of the type where perforated plates, honeycombs or other physical structures are utilized to provide physical confinement for each individual discharge unit.

The gas may be conditioned (e.g., provided with a supply of free electrons) for the ionization process by application of an initial tiring potential to a selected pair of conductors tor sufficient time to effect an initial discharge in a discrete gas volume, as for example a discharge at the discharge unit consisting of the crossing or shadow area of conductors llZ-l and ill-d1, the dielectric on those conductors at those crossings or shadow areas and the discrete volume of gas therebelween, the volume of gas permitting photonic communication between all discharge units so that photons which strike or im pact the dielectric surfaces produce or cause the release of electrons. Alternatively, the gas may be conditioned by providing an exterior source of ultraviolet radiation for producing by photoelectric emission free electrons for the ionization process or by placing a radioactive material in the glass or gas space which likewise can etilect the presence of sufficient free electrons within the gas space for ionization at uniform potentials for a given gas, pressure, panel configuration, etc. At any rate, the invention will be described further in connection with a gas volume (whether unconfined as in the above-referenced Baker et al. patent: or confined by a honeycomb or cellular structure as in the prior art) that has been conditioned for the ionization process.

individual discharge units may be turned on" (a sequence of momentary discharges on alternate halt cycles of applied alternating potential following an initial discharge) and off (termination of the sequence) by many different waveforms, the simplest of which is the sinusoidal voltage waveform. Basically, the only condition other than the voltage waveform is that the discharge unit be conditioned such that it is responsive to the applied voltage.

The pulse generator circuit for addressing a conductor ofan individual discharge unit is disclosed in FlG. 2 and includes a first transistor Ql having base 3d, collector 3i and emitter 32 electrodes with collector electrode Ill connected directly to a direct current supply Vll and the emitter electrode 32 con nected to ground through resistance 33. An input logic signal 34 (about 4 volts having a duration of about [00 nanoseconds) is applied to base electrode Bill. This transistor Ql operates as an amplifier and its output is coupled from emitter 32 directly to base electrode 3d of a second transistor Q2. The emitter electrode oi transistor Q2 is connected directly to ground and collector electrode is connected through a small series resistor 39 to primary winding ilt of a transformer Tl. The upper end of the primary winding of transformer Tl is connected to relatively high direct current voltage V2 and a diode D11 is connected in shunt or parallel with the primary winding ill of transformer Tl.

When a logic pulse M from addressing logic circuit til is ap plied to the base 3d of transistor l'lQl, this transistor increases the power level sufficiently to turn on transistor 02. in a switching model This switching action is rapid so that a current surge flows through the primary winding ill of transformer Tl causing a voltage pulse to he produced on the secondary winding. At the end oftlie input pulse 34, transistor Q2 will turn off stopping the current flow in the primary winding id of transformer Ti and a second voltage pulse on the secondary d2 of the transformer is prevented by the diode D1. The diode Di clips the negative part of the oscillation giving it single half-wave output pulse. This diode D1 also serves to protect the transistor Q2 from large transients which may occur during the turn off operation. As a practical matter, the input logic pulse 34 is made to have a duration less than half the period to take into account the transistor stored charge which may delay the turning off time of the transistor after the input signal is removed. Addressing logic circuit 61 while complex is conventional and may be of the line scan type or random access type, either of which can supply logic pulses 34 at selected time intervals.

The secondary winding 42 of the transformer T1 is in series circuit with the sustaining signal generator 29 and the line (conductor of the conductor array) being addressed so that the two voltages are added. In order to minimize interaction, the resonant frequency of the sustaining generator and the resonant frequency of the pulse generator are preferably made different so as to reduce power drain and provide maximum signal for application to the panel. The on-off pulse is adjusted for about a l-microsecond duration and the sustaining signal period is about microseconds, however, the invention is not limited to these particular time ratios.

The display panel requires a continuous signal applied to all lines, which is referred to as the sustaining signal or voltage. By continuous signal it is meant that the voltage be periodic so that it may be of the simple sinusoidal-type or a complex wave shape applied for short time intervals and repeated periodically. The invention will be described in connection with a sinusoidal voltage waveform in the 50 to 500 Hz. range. The same sustaining voltage is applied to all X" lines and a similar voltage is applied to all Y lines but at a 180 phase relationship (see FIG. 3). These voltages, as applied to conductors of the conductor arrays on the panel, are balanced with respect to ground to permit the addressing of a single discharge unit within the panel.

In order to lessen the effect of variable capacitive loading on the sustaining voltage generator 29, a capacitance 45 may be connected in shunt with the panel, the larger the panel capacitance change as more discharge units are turned on, being accommodated by a larger shunt capacitance.

As shown in FIG. 1A, each line on conductor of a conductor array is provided with a pulse generator 60 (e.g., 60-12-1 60-12-n and 60-13-1 60-13n which receives a trigger input (logic pulse 34) from addressing circuit 61. For example, when it is desired to address or turn on the discharge unit defined by the crossing of conductors 13-1 and 12-], a logic pulse is applied simultaneously to pulse generator circuit 60-13-1 and 60-12-1 so that unidirectional pulses are added to the out of phase voltages, respectively, from sustaining voltage generator 29. A synchronization connection 90 between sustaining generator 29 and addressing logic circuit 61 is provided so that the logic pulses 34 occur at proper times with respect to the sustaining voltage from sustaining voltage generator 29.

The on-"off" state of a discharge unit is indicated in F168. 4-7 wherein the lower voltage trace 66 is the voltage output from a photomultiplier (not shown) sensing the individual light bursts emitted from a discharge unit. As earlier noted, a unit discharges or fires twice per cycle of the applied sustaining voltage. The area of photomultiplier voltage pulse varies with the number of electrons involved in a single discharge, and may be taken as an approximate measure of the change in the discharge unit bias voltage. This bias voltage is not an applied voltage as such but is the result of the collection of electrons and ions on opposing discrete surface areas 17 and 18 at each individual discharge unit. The direction of the electric field resulting from the collection of electrons and ions on such surfaces is opposite to the direction of applied field creating (via ionization) them and hence serve to terminate the discharge and thus, the bias voltage alternates with the alternation in direction of applied field and, in opposite directions thereto.

If a sinusoidal voltage on a discharge unit is raised in magnitude to the breakdown level (the firing potential) the discharge unit will discharge. If the amplitude of the applied potential is reduced, the discharge unit will continue to stay on and, in fact, the discharge unit will stay on down to some minimum level of sustaining voltage at which point the discharge unit will go off so that if the applied alternating potential voltage is less than the breakdown or firing voltage but greater than the sustaining voltage level the discharge unit will continue to be in a single firing state. This difference between on" and off voltage levels is utilized as an electrical memory and, as noted above, it is due to alternate storage of charges on the surfaces 17 and 18 of dielectric members 14 and 16 to constitute a discharge unit bias or memory voltage. Where the discharge units are arrayed in horizontal rows and vertical columns served by horizontal and vertical conductor arrays it is important to be able to alter the state of one discharge unit while not affecting the status of others. Moreover, for simplicity purposes, it is desirable to utilize a sinusoidal signal that is at or slightly greater than the sustaining level and to utilize additive voltages on certain conductors to modify the status of selected discharge units.

As suggested above, when a discharge unit discharges, electrons and ions flow across the gas gap in a direction such as to reduce the effect of applied voltage. If the discharge time internally is very short (in the nanosecond range) then the applied voltage does not change appreciably and the change in the voltage across the discharge unit is equal to the breakdown voltage. This presumes that the discharge does not cease at a nonzero voltage, but continues to zero. It was thought that a discharge unit was turned on" by raising the voltage to the firing potential, and by gradual reduction of voltage to a sustaining level at a rate slow enough to permit the discharges to track. Turn ofF was thought to be accomplished by causing a discharge to occur at a time when the applied voltage was zero. Since the discharge would take the discharge voltage unit to zero, the bias voltage would be reduced to zero causing the discharge unit to be in the off state. This, however, does not adequately describe the actual operation for it has been found that a discharge unit can be fired when the applied voltage is zero and still remains in the active state, that is the bias voltage due to charge storage is not reduced to zero.

FIG. 4 illustrates the turn on sequence in accordance with the invention. In this waveform diagram, and in those to follow, the dots 70 are superimposed upon the sustaining signal waveform and symbolize a light-producing momentary or pulse discharge of a discharge unit and the lower traces symbolize or represent the output of a photomultiplier which has been directed or aimed to a given discharge unit. In other words, the photomultiplier output has been superimposed or added to the sustaining waveform to indicate individual discharge points or firing times during an applied sustaining voltage and as shown, there will be two discharges or pulses of light produced for every full cycle of applied sustaining voltage (light-producing discharges on positive half-cycles being identified as 751 and light-producing discharges on negative half-cycles being identified as 75N) once the unit has been discharged or fired. The voltage 71 is the output from the pulse-forming circuit which as been added to the sustaining voltage 72. The first discharge 73 is due to the increased applied voltage across the discharge unit (which is the sum of the sustaining voltage and the applied pulse added thereto). Following'the application of the initial firing or turn on pulse 71 to the sustaining voltage 72, there is a second momentary discharge represented by the photomultiplier output 74. The voltage time characteristics of applied voltage influences the amount of charge stored on the discharge unit at the end of discharge 73. The stored charge resulting from discharge 73 must be such that discharge 74 will involve that amount of charge necessary to bias the discharge unit on" so that when the sustaining voltage goes to its positive peak another discharge takes place near the normal discharge point of an on" discharge unit. Thereafter, the selected discharge unit continues to fire as a normally "on" discharge unit. Since each discharge is terminated upon a buildup or storage of charges at opposed pairs of elemental areas, light produced is likewise terminated. in fact, light production lasts for only a small fraction of a half-cycle of applied alternating potential. Storage of such charges constitutes an electrical memory and such stored charges constitute a bias voltage or memory which will effect a discharge again at or near the peak of the half-cycle of sustaining voltage to again produce a momentary pulse of light. At this time, due to reversal of field direction, electrons and ions will collect on respective surfaces of the dielectric and after a few cycles of voltage the times of discharges (as represented by dots 7h) become symmetrically located with respect to the waveform of sustaining voltage.

in order to turn off a selected discharge unit (e.g., terminate a sequence of discharges representing the on state), the stored charges (which constitute a discharge unit bias voltage) must be eliminated or modified in such a way that the amplitude of applied voltage, which is the constant amplitude sustaining voltage 72, will be insufiicient to effect a discharge. The turn off pulse is identical to the turn on pulse. It has been found that a discharge unit may be turned off in several different ways, depending on the time of application of the turn off pulse with respect to the sustaining voltage. Three turnoff methods are illustrated in N65. 5, s and 7, respectively. These three turn off methods are illustrated in lFlGS. 5, 6 and 7, respectively. in H6. ti, prior to application of pulse the discharge unit is on and discharging in a single firing mode, namely, twice per cycle (as represented by clots 7d and photomultiplier pulses 751i and 75W). The pulse 8f) is synchronized in time so the pulse tip or peak occurs at the point of discharge Till. Due to the applied voltage time characteristics of the applied voltage, the amount of charge transferred is reduced so as to reduce the discharge unit bias voltage below the sustaining level. That is, the amount of charge stored on the dielectric surfaces is insufficient to result in a potential or field which augments the sustaining voltage to produce a discharge. Thus, the discharge unit is turned off. Note that the reduced discharge is indicated by the corresponding photomultiplier pulse 7d and the last photomultiplier pulse is considerably shorter than the previous positive cycle photomultiplier pulses indicating a reduction in stored charge.

The second turn of method is illustrated in FIG. 6. This method differs from the first in that the turn off is accomplished by modifying the voltage time characteristics on the next to the last normal discharge. The voltage time characteristics of the applied voltage till is increased on the last positive discharge hill? so as to increase the stored charge and reduce the applied voltage necessary to sustain successive discharge. This modifies the bias voltage on the next negative discharge such that the discharge unit will be left with a bias voltage insufficient to tire on the next positive cycle. The third method of turning of a discharge unit is illustrated in FIG. 7. This method is similar to the first in that turn off is achieved by combining the voltage waveforms of pulse d3 and sinusoidal voltage '72 in such a way as to turn off" the discharge unit at the point of the last discharge. hlOtice, however, that the methods differ in that the former turn of is done on a positive cycle and the latter on the negative cycle.

Thus, when it is desired to turn off an on discharge unit, the turn off" pulse is applied in such a fashion as to alter the amount of charge produced in one of the discharges, thus altering the bias voltage in such a way as to terminate the sequence of discharges.

The high voltage requirement (up to about 1 ltv.) and frequency range of interest (50 to 500 kHz.) determine the current requirements across the panel and shunt capacitance 45.

With reference to t lt l/t, capacitor did may be part ofa series tuned circuit including generator hi and is used to offset both the panel capacitance change and resistive change during a cycle from where no discharge'units of a line are 011" to where all discharge units are on." However, it is desirable to keep capacitor as small as possible so as to limit the required driving current.

The invention is not to be limited to the precise form shown in the drawings for obviously many changes may be made, some of which are suggested herein, within the scope of the following claims.

5 What is claimed is:

i. in an interfacing circuit for a gas discharge panel of the type in which a discharge in a hermetically enclosed ionizable gas generates charges alternately collectable on a pair of discrete areas of a pair of means having dielectric surfaces, said dielectric surfaces being backed by row and column conductor arrays, respectively, defining a plurality of pairs of opposed discrete charge storage areas, means supplying a pair of oppositely phased periodic alternating sustaining voltages connected to said row and column conductor arrays, respectively, the charges, once created and stored at a pair of said discrete areas first, terminating a discharge within a fraction of a halfcycle of said applied sustaining voltage, and second, acting with said applied sustaining voltage on the next half-cycle of sustaining voltage to cause a second discharge, and repeating the sequence of discharge for each succeeding half-cycle of applied sustaining voltage,

an addressing circuit for selecting individual ones of said row and column conductors,

unidirectional voltage pulse generator means controlled by said addressing circuit for producing a pair of oppositepolarity high-voltage unidirectional pulses, each having a time duration relatively short with respect to a cycle of said periodic alternating sustaining voltage, and

means for algebraically adding a iirst of said high-voltage unidirectional pulse pairs to said pair of oppositely phased periodic alternating sustaining voltages, respectively, applied to a selected conductor pair of said conductor arrays and during an amplitude excursion thereof in the same direction as said unidirectional pulse to cause a discharge in the selected gas discharge unit and produce charges for storage at the charge storage areas defined by the selected row and column conductor pair, and initiating the sequence of discharges on each half-cycle of applied sustaining voltage, and algebraically adding the next succeeding of said high-voltage unidirectional pulses, having a time duration which is short relative to said alternating sustaining voltage, at a time in a half-cycle period thereof to rapidly modify the storage of charge at said selected charge storage area and terminate the storage of charges at said selected charge storage areas to terminate the sequence of discharges.

2. The invention defined in claim l wherein said means controlled by said addressing circuit includes, with respect to the 50 row and column conductor arrays, respectively.

a source of direct current,

a normally open switch,

an induction device connected in series circuit with said switch and said source of direct current,

means for operating said switch in accordance with a signal from said addressing circuit to cause a current surge to flow through said induction device and produce said highvoltage unidirectional pulses to be algebraically added to said sustaining voltage to initiate and terminate said sequence of discharges, respectively.

3. The invention defined in claim It. wherein said induction device is a transformer having a primary and a secondary winding, said primary winding being connected in series circuit with said source, said secondary winding being connected 65 in series with said source of periodic alternating sustaining voltage,

and means connected to said ringing currents.

i. A method of controlling the discharge of selected 70 discharge units of a multiple-discharge gaseous display/memory device of the type in which a discharge in a hermetically enclosed ionizable gas generates charges alternately collectablc on a pair of discrete areas of a pair of means having dielectric surfaces to constitute an internal bias voltage on the gas, each 75 of said dielectric surfaces being backed by a row-column conprimary winding to suppress ductor matrix array defining a plurality of pairs of opposed discrete areas, comprising,

supplying a first potential to all conductors of said array, said first potential being a periodically applied alternating voltage of amplitude insufficient to initiate a discharge and generate said charges at any discharge unit, but of sufficient magnitude to sustain one or more discharge units in a discharged state with the aid of said internal bias voltage following an initial discharge therein,

selectively algebraically adding to said first potential during an amplitude excursion thereof a first unidirectional pulse to a selected pair of crossing conductors of said array to turn on a selected discharge unit located at the crossing point of said selected pair of crossing conductors,

and selectively algebraically adding to said first potential at a selected subsequent time, and in a time period during a half-cycle thereof, a second unidirectional voltage pulse to rapidly terminate production and alternate collection of charges at said areas defined by said selected conductors and rapidly eliminate said internal bias field.

5. The method defined in claim 4 wherein said second unidirectional pulse is applied to said periodic first potential at a time when said first periodic potential reaches an amplitude sufficient to discharge the selected discharge unit in one direction.

6. The method defined in claim 5 wherein said second unidirectional pulse is applied at a time when the periodic first potential is increasing in amplitude in the same direction as said unidirectional pulse.

7. In a gas discharge panel of the type in which a discharge in a hennetically enclosed ionizable gas generates charges alternately collectable on a pair of discrete areas of a pair of means having dielectric surfaces, said dielectric surfaces being backed by row and column conductor arrays, respectively, cooperatively defining a plurality of pairs of opposed discrete charge storage areas and means supplying a pair of oppositely phased periodic alternating sustaining voltage connected to said row and column conductor arrays, respectively, the charges, once created and stored at a pair of said discrete areas, first terminating a discharge within a fraction of a halfcycle of said applied sustaining voltage, and, second, acting with said applied sustaining voltage on the next half-cycle of sustaining voltage to cause a second discharge, and repeating the sequence of discharge for each succeeding half-cycle of applied sustaining voltage, and an addressing circuit for selecting individual ones of said row and column conductors, the improvement comprising,

unidirectional voltage pulse circuit means controlled by low-level logic signals from said addressing circuitfor producing a pair of opposite-polarity high-voltage unidirectional pulses, each unidirectional pulse having a time duration relatively short with respect to a cycle of said periodic alternating sustaining voltage, and

circuit means for l. algebraically adding a first pair of opposite polarity high-voltage unidirectional pulses to said pair of oppositely phased'periodic alternating sustaining voltages, respectively, applied to a selected row and column conductor pair of said conductor arrays and cause a discharge in the selected gas discharge unit and produce charges for storage at the charge storage areas defined by the selected row and column conductor pair, and initiating the sequence of discharges on each half'cycle of applied sustaining voltage, and

. algebraically adding the next succeeding of said pair of opposite-polarity high-voltage unidirectional pulses, having a time duration which is short relative to said alternating voltage, at a time in a half-cycle thereof to rapidly modify the storage of charge at said selected charge storage area and terminate the storage of charges at said selected storage areas to terminate the sequence ofdischarges 8. The invention defined in claim 7 wherein said circuit means for algebraically adding includes a transformer secondary winding in series circuit with said sustaining voltage supply for a plurality of conductors on said panel.

9. A method of controlling the discharge conditions of selected discharge units ofa multiple discharge gaseous display/memory device of the type in which a discharge in a hermetically enclosed ionizable gas generates charges alternately collectable on a pair of discrete areas of a pair of means having dielectric surfaces to constitute an internal bias voltage on the gas, each of said dielectric surfaces being backed by a rowcolumn conductor matrix array defining a plurality of pairs of opposed discrete areas, comprising,

continuously applying a first potential to all conductors of said array, said first potential being a periodic alternating voltage of amplitude insufficient to initiate a discharge and generate said charges at any discharge unit, but of sufficient magnitude to sustain said discharge units in a discharged state with the aid of said internal bias voltage following on initial discharge therein,

selectively algebraically adding to said first potential a first unidirectional pulse to a selected pair of crossing conductors of said array to cause in an initial discharge at a selected discharge unit located at the crossing point of said selected pair of crossing conductors, and

selectively algebraically adding to said first potential,

without interruption in the period thereof, at a selected subsequent time during a half-cycle thereof a second unidirectional voltage pulse to rapidly terminate production and alternate collection of charges at said areas defined by said selected conductors and rapidly eliminate said internal bias field.

10. The invention defined in claim 9 wherein the steps of selectively algebraically adding said unidirectional pulses to said first potential is by inductively inducing said unidirectional voltage pulses in a series circuit with the source of first potential for each row-column conductor, respectively. 

1. In an interfacing circuit for a gas discharge panel of the type in which a discharge in a hermetically enclosed ionizable gas generates charges alternately collectable on a pair of discrete areas of a pair of means having dielectric surfaces, said dielectric suRfaces being backed by row and column conductor arrays, respectively, defining a plurality of pairs of opposed discrete charge storage areas, means supplying a pair of oppositely phased periodic alternating sustaining voltages connected to said row and column conductor arrays, respectively, the charges, once created and stored at a pair of said discrete areas first, terminating a discharge within a fraction of a halfcycle of said applied sustaining voltage, and second, acting with said applied sustaining voltage on the next half-cycle of sustaining voltage to cause a second discharge, and repeating the sequence of discharge for each succeeding half-cycle of applied sustaining voltage, an addressing circuit for selecting individual ones of said row and column conductors, unidirectional voltage pulse generator means controlled by said addressing circuit for producing a pair of opposite-polarity high-voltage unidirectional pulses, each having a time duration relatively short with respect to a cycle of said periodic alternating sustaining voltage, and means for algebraically adding a first of said high-voltage unidirectional pulse pairs to said pair of oppositely phased periodic alternating sustaining voltages, respectively, applied to a selected conductor pair of said conductor arrays and during an amplitude excursion thereof in the same direction as said unidirectional pulse to cause a discharge in the selected gas discharge unit and produce charges for storage at the charge storage areas defined by the selected row and column conductor pair, and initiating the sequence of discharges on each half-cycle of applied sustaining voltage, and algebraically adding the next succeeding of said high-voltage unidirectional pulses, having a time duration which is short relative to said alternating sustaining voltage, at a time in a half-cycle period thereof to rapidly modify the storage of charge at said selected charge storage area and terminate the storage of charges at said selected charge storage areas to terminate the sequence of discharges.
 2. The invention defined in claim 1 wherein said means controlled by said addressing circuit includes, with respect to the row and column conductor arrays, respectively. a source of direct current, a normally open switch, an induction device connected in series circuit with said switch and said source of direct current, means for operating said switch in accordance with a signal from said addressing circuit to cause a current surge to flow through said induction device and produce said high-voltage unidirectional pulses to be algebraically added to said sustaining voltage to initiate and terminate said sequence of discharges, respectively.
 2. algebraically adding the next succeeding of said pair of opposite-polarity high-voltage unidirectional pulses, having a time duration which is short relative to said alternating voltage, at a time in a half-cycle thereof to rapidly modify the storage of charge at said selected charge storage area and terminate the storage of charges at said selected storage areas to terminate the sequence of discharges.
 3. The invention defined in claim 2 wherein said induction device is a transformer having a primary and a secondary winding, said primary winding being connected in series circuit with said source, said secondary winding being connected in series with said source of periodic alternating sustaining voltage, and means connected to said primary winding to suppress ringing currents.
 4. A method of controlling the discharge of selected discharge units of a multiple-discharge gaseous display/memory device of the type in which a discharge in a hermetically enclosed ionizable gas generates charges alternately collectable on a pair of discrete areas of a pair of means having dielectric surfaces to constitute an internal bias voltage on the gas, each of said dielectric surfaces being backed by a row-column conductor matrix array defining a plurality of pairs of opposed discrete areas, comprising, supplying a first potential to all conductors of said array, said first potential being a periodically applied alternating voltage of amplitude insufficient to initiate a discharge and generate said charges at any discharge unit, but of sufficient magnitude to sustain one or more discharge units in a discharged state with the aid of said internal bias voltage followinG an initial discharge therein, selectively algebraically adding to said first potential during an amplitude excursion thereof a first unidirectional pulse to a selected pair of crossing conductors of said array to turn on a selected discharge unit located at the crossing point of said selected pair of crossing conductors, and selectively algebraically adding to said first potential at a selected subsequent time, and in a time period during a half-cycle thereof, a second unidirectional voltage pulse to rapidly terminate production and alternate collection of charges at said areas defined by said selected conductors and rapidly eliminate said internal bias field.
 5. The method defined in claim 4 wherein said second unidirectional pulse is applied to said periodic first potential at a time when said first periodic potential reaches an amplitude sufficient to discharge the selected discharge unit in one direction.
 6. The method defined in claim 5 wherein said second unidirectional pulse is applied at a time when the periodic first potential is increasing in amplitude in the same direction as said unidirectional pulse.
 7. In a gas discharge panel of the type in which a discharge in a hermetically enclosed ionizable gas generates charges alternately collectable on a pair of discrete areas of a pair of means having dielectric surfaces, said dielectric surfaces being backed by row and column conductor arrays, respectively, cooperatively defining a plurality of pairs of opposed discrete charge storage areas and means supplying a pair of oppositely phased periodic alternating sustaining voltage connected to said row and column conductor arrays, respectively, the charges, once created and stored at a pair of said discrete areas, first terminating a discharge within a fraction of a half-cycle of said applied sustaining voltage, and, second, acting with said applied sustaining voltage on the next half-cycle of sustaining voltage to cause a second discharge, and repeating the sequence of discharge for each succeeding half-cycle of applied sustaining voltage, and an addressing circuit for selecting individual ones of said row and column conductors, the improvement comprising, unidirectional voltage pulse circuit means controlled by low-level logic signals from said addressing circuit for producing a pair of opposite-polarity high-voltage unidirectional pulses, each unidirectional pulse having a time duration relatively short with respect to a cycle of said periodic alternating sustaining voltage, and circuit means for
 8. The invention defined in claim 7 wherein said circuit means for algebraically adding includes a transformer secondary winding in series circuit with said sustaining voltage supply for a plurality of conductors on said panel.
 9. A method of controlling the discharge conditions of selected discharge units of a multiple discharge gaseous display/memory device of the type in which a discharge in a hermetically enclosed ionizable gas generates charges alternately collectable on a pair of discrEte areas of a pair of means having dielectric surfaces to constitute an internal bias voltage on the gas, each of said dielectric surfaces being backed by a row-column conductor matrix array defining a plurality of pairs of opposed discrete areas, comprising, continuously applying a first potential to all conductors of said array, said first potential being a periodic alternating voltage of amplitude insufficient to initiate a discharge and generate said charges at any discharge unit, but of sufficient magnitude to sustain said discharge units in a discharged state with the aid of said internal bias voltage following on initial discharge therein, selectively algebraically adding to said first potential a first unidirectional pulse to a selected pair of crossing conductors of said array to cause in an initial discharge at a selected discharge unit located at the crossing point of said selected pair of crossing conductors, and selectively algebraically adding to said first potential, without interruption in the period thereof, at a selected subsequent time during a half-cycle thereof a second unidirectional voltage pulse to rapidly terminate production and alternate collection of charges at said areas defined by said selected conductors and rapidly eliminate said internal bias field.
 10. The invention defined in claim 9 wherein the steps of selectively algebraically adding said unidirectional pulses to said first potential is by inductively inducing said unidirectional voltage pulses in a series circuit with the source of first potential for each row-column conductor, respectively. 